1. addons : Contains packages required in order to build the main Distribution or packages produced by SRPMS built in the main Distribution, but not included in the main Redhat package tree (mysql- server in CentOS-3.x falls into this category). Packages contained in the addons repository should be considered essentially a part of the core distribution, but may not be in the main Redhat Package tree. 2. apt : Contains all the apt RPMS for the CentOS site. This is where you would point if you want to use apt to do updates. Apt has issues with distros that use multiple libraries, so is only available for the i386 distro. 3. centosplus : Packages contributed by CentOS Developers and the Users. These packages might replace rpm's included in the core Distribution. You should understand the implications of enabling and using packages from this repository. 4. contrib : Packages contributed by the CentOS Users, which do not overlap with any of the core Distribution packages. These packages have not been tested by the CentOS developers, and may not track upstream version releases very closely. 5. docs : Contains manuals and release notes for CentOS 6. extras : Packages built and maintained by the CentOS developers, that add functionality to the core distribution. These packages have undergone some basic testing, should track upstream release versions fairly closely and will never replace any core distribution package. 7. isos : Contains the ISOs for download. On the main CentOS mirror sites ISOs can not be downloaded directly, but we provide a Bittorent file for downloading. On external public mirrors, ISOs may be downloadable directly. 8. os : Contains the base OS files that are on the Main ISO files. 9. updates : Contains updates released for the CentOS distro. ---- We welcome contributions into the Contrib and CentOSPlus repository. Post a message on the CentOS-Devel mailing list with details of packages you would like to contribute, one of the CentOS developers will then pick it up and work with you on the issue. You might want to make sure that the same package is not already easily available from some other mainstream repository. And, you should be willing to maintain the packages in sync with upstream releases and fix's.